The Role of Milk and Dairy Products in Type 2 Diabetes and Prediabetes: A Narrative Review of Randomized Trials

Background/Objectives: The influence of milk and dairy products on glucose metabolism, prediabetes and type 2 diabetes is controversial. The topic has taken on new relevance following the release of the new U.S. Dietary Guidelines For Americans, recommending full-fat dairy with no added sugars on a daily basis. The purpose of this narrative review is to summarize evidence from randomized trials on the potential effects of milk and dairy products on glycemic parameters. Methods: For this narrative review we conducted a PubMed literature search for randomized controlled trials with combined search terms (dairy AND diabetes mellitus type 2) OR (dairy products AND diabetes mellitus type 2) OR (dairy AND pre diabetes) OR (dairy products AND pre diabetes). Eligible trials enrolled adults with prediabetes or type 2 diabetes and analyzed the influence of a milk or dairy-product intervention on glycemic markers. Included trials had full text availability and were published in English or German. Results: After screening for inclusion criteria, we identified 46 studies for type 2 diabetes and 11 trials for prediabetes. Findings of included studies are presented categorized by type 2 diabetes and prediabetes cohorts, by dairy intervention and by effects on acute (e.g. postprandial glucose, insulin and incretin concentrations) and chronic (e.g. hemoglobin A1c, fructosamine) glycemic control. Conclusions: Dairy products require a differentiated view, as their glycemic effects in people with type 2 diabetes or prediabetes vary substantially by dairy matrix, dose, timing, and specific fortification.